We had originally planned to go all-in on passkeys for ONCE/Campfire, and we built the early authentication system entirely around that. It was not a simple setup! Handling passkeys properly is surprisingly complicated on the backend, but we got it done. Unfortunately, the user experience kinda sucked, so we ended up ripping it all out...
I think that passkeys are simple, but no-one explains what they do and don’t do in specific terms.
Someone compared it to generating private/public key pairs on each device you set up, which helps me a bit, but I recently set up a passkey on a new laptop when offered and it seemed to replace the option to use my phone as a passkey for the same site (which had worked), and was asking me to scan a QR code with my phone to set it up again.
So I don’t know what went on behind the scenes there at all.
The passkey on your phone stopped working when you set one up on your laptop? I would expect the site to allow one per device instead of one per account.
It seemed that way, it asked me to scan a QR code on my phone to link it, which didn’t happen before.
Or maybe the option to use my phone was some older auth method, where I’d use the fingerprint reader on the phone to confirm a login on the laptop. I thought that was a passkey, but that doesn’t fit with what I’m reading about what it does now.